Cellulose reinforced resin compositions with wax blend

ABSTRACT

The present invention provides an extrudable reinforced resin-containing composition comprising resin capable of plastic flow, reinforcing material, and a lubricant composition comprising oxidized polyethylene wax, ester wax, and amide wax. Also provided are the lubricant composition, and extrusion methods and extruded products based on the present compositions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority of PCT Application No.PCT/US04/07657 filed on Mar. 12, 2004, and U.S. Provisional ApplicationSer. No. 60/454,834, filed on Mar. 14, 2003, the contents of which arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

Extrusion feedstock compositions comprising cellulose fiber, forexample, wood fiber, and a resin, for example, a thermoplastic resin,for example, polyvinyl chloride resin, are well known. Examples of suchcompositions are described in U.S. Pat. Nos. 6,103,791 and 6,248,813 toZehner and U.S. Pat. No. 6,210,792 to Seethamraju et al, which arehereby incorporated by reference. These compositions can be extruded toprovide shaped articles, for example, decorative molding for finishcarpentry. Compositions based on polyvinyl chloride resins (PVC) arepreferred for such applications because of their superiorweather-resistant properties over other types of resin compositions.

In general extrusion of material reinforced thermoplastic resincompositions, for example a cellulose/polyvinyl chloride resincomposition requires heating an extrudable mixture to a temperature atwhich it can undergo plastic flow, and then forcing it through a platecontaining one or more openings (herein, a “die”) which impart a profileshape to the emerging extrudate. As it emerges from the orifice opening,the extrudate is cooled until it becomes rigid, retaining the profileshape. The shaped extrudate is used either in its extruded form, forexample, as a decorative molding, or it is cut into convenient lengthpieces and packaged for use in follow-on processing, for example, asfeedstock for an injection or blow molding process.

In general an extrusion feedstock composition, also referred to hereinfor convenience as “an extrudable composition”, is often prepared bycombining cellulose fiber and a resin, for example, a thermoplasticresin, for example, polyvinyl chloride (PVC) resin, and otherconstituents (also called additives) which effect the properties of thecomposition and the extrudate, for example, a lubricant. Other examplesof constituents which may be included in an extrudable composition, forexample, one containing a PVC resin, are those described in the Handbookof Plastic Materials and Technology, Ed. I. Rubin, Wiley-Interscience,John Wiley & Sons, Inc. New York, 1990 and Plastics Additives andModifiers Handbook, Ed. J. Edenbaum, Van Nostrand Reinhold, New York1992, Chapter 3, each of which is incorporated herein by reference.Examples of additional constituents (additives) include fillers (forexample, calcium carbonate), processing aids (for example acryliccopolymers), and stabilizers for imparting heat stability to thecomposition during the extrusion process (for example, tin basedstabilizer such as TM281® from Rohm & Haas).

Once combined, the constituents of the composition are “fused,” that is,subjected to heating and blending until there is formed a plasticcomposition which is substantially homogeneous. The term “fusion” isapplied to this process because in heating and blending the boundariesof the individual granules of the constituents become indistinguishable,thus, “fused”. The various additives and the amounts of the additivesused influence the properties of the composition and its performanceduring and after extrusion. Examples of properties effected include theprocessability of the material during extrusion or in follow-onprocesses in which the extruded material is employed and the physicaland mechanical properties of an extrudate made from the composition.Examples of physical properties are the dimensional stability andsurface gloss of the extrudate product prepared from the extrudablecomposition. Examples of mechanical properties include the flexural andtensile strength of an extrudate prepared from the extrudablecomposition. Examples of extrudability properties of the extrudablecomposition include the extrusion rate of the composition for a givenextruder torque setting or value of head pressure

Dimensional stability and surface appearance (surface gloss) arecharacteristics that may affect the commercial value of an extrudedproduct and hence of the processes and the components used to make theextruded product. Dimensional stability is assessed by observing theamount by which an extruded shape expands during solidification after itemerges from the die of an extrusion apparatus. The amount of expansionis sometimes referred to as die swell. Surface gloss is measured inaccordance with known standard measurements, for example, ASTM standardsD-2523-95 and D2457-97

The tensile and flexural strength of extruded articles are important tothe commercial value of an extruded product also. These mechanicalproperties can be effected by the type and amount of lubricant includedin the extrudable composition preparatory to producing the extrudedarticle. These mechanical properties can be measured in accordance withknown standard measurements, for example ASTM standards D 638 and D 6109for measurement of the tensile and flexural strength of an extrudedarticle, respectively

For a given extrudable composition, it is generally possible to increasethe rate at which material is extruded. However, such extrusion rateincreases have practical limitations. For example, it is possible toobtain extrusion rate increases by operating the extruder at a highertemperature and/or at a higher head pressure. However, at some point ofincreasing extruder temperature the extrudable composition willgenerally begin to scorch, and the surface and structural qualities ofthe extrudate will begin to degrade. Furthermore, as the head pressureor extruder torque is increased, a point is generally reached at whichthe dimensional stability and/or surface condition of the extrudedmaterial is unacceptable. These process limitations have createdpractical limits on the rate at which prior compositions could beextruded.

Another mechanism that is at least theoretically available to achievehigher extrusion rates is to increase the amount and/or type oflubricant incorporated into the extrudable composition. However, it isalso possible that increasing the amount of the lubricant or changingthe type of lubricant can have deleterious effects on the extrudedproduct, for example, compromising one or more of the inherent physicaland/or mechanical properties of the product (extrudate) and/or on otheraspects of the extrusion process.

Reduction in the tensile strength of an extrudate is an example of oneinherent mechanical property of an extrudate which may be compromised byincreasing the amounts of certain lubricants or other additives. Inparticular, increasing amounts of certain lubricants known as externallubricants in reinforced resin extrudates, for example, cellulosereinforced PVC extrudates, can reduce the adhesion of the PVC resin tothe reinforcing material, negatively impacting the strength of theextrudate and its surface appearance. Also, increased amounts ofexternal lubricant may negatively impact not only the strength of theextrudate but may also increase the fusion time, which increases theoverall processing time.

Applicants have thus come to recognize the need for cellulose reinforcedextrudable compositions, particularly extrudable PVC-based compositions,having one or more of those desirable extrusion characteristicsassociated with high levels of lubricant while reducing or substantiallyeliminating one or more or the adverse effects that would otherwise beassociated with a high level of lubricant. The present methods andextrudable compositions meet this and other needs.

SUMMARY OF THE INVENTION

One aspect of the present invention provides extrudable compositions;more preferably, cellulose reinforced extrudable compositions comprisinga thermoplastic resin for example, polyvinyl chloride (PVC), and alubricant composition comprising at least one oxidized polyethylene wax,at least one ester wax, and at least one amide wax. Other additives mayalso be present in the extrudable compositions of the present invention.Applicants have discovered that the presence of a lubricant compositionof the present invention in a cellulose-containing extrudable PVCcomposition, in preferred embodiments, results in an extrudablecomposition which exhibits a highly desirable yet difficult to obtaincombination of properties. For example, in certain preferred embodimentsthe present extrudable compositions are capable of being extruded atadvantageously high extrusion rates, and yet provide extrudate ofrelatively high tensile strength and/or high flexural strength and/orhigh surface gloss.

In preferred embodiments, the extrudable composition of the presentinvention comprises an amount of the present lubricant compositioneffective to achieve one or more of the following characteristicsrelative to the extrudable composition without the lubricant composition(assuming all other extrusion parameters remain substantially constant):(i) decreased extrusion pressure for a given die and extrusion rate;(ii) reduced fusion temperature; (iii) reduced amount of stabilizerneeded to achieve the same degree of stability; (iv) increased tensileand/or flexural strength of an article formed from the extrusion of theextrusion mixture; or (v) visibly reduced surface roughness of anarticle formed from the extrusion of the extrusion mixture.

The present invention also includes as another aspect a lubricantcomposition comprising at least one oxidized polyethylene wax, at leastone ester wax, and at least one amide wax. Other additives may beincluded in the present lubricant compositions.

Another aspect of the present invention involves processes for extrudinga cellulose reinforced thermoplastic composition, preferably a polyvinylchloride-based composition. The process preferably comprises:

a) providing an extrudable thermoplastic composition comprising at leastone thermoplastic polymer and a lubricant composition comprising atleast one oxidized polyethylene wax, at least one ester wax, and atleast one amide wax; and

b) extruding said extrudable mass to form a shaped article.

The present lubricant composition is preferably present in the presentextrudable composition in an amount effective to improve theextrudability of the extrudable composition, as measured relative to theextrudability of the extrudable composition in the absence of thelubricant composition, preferably by at least about 10 percent, morepreferably by at least about 20 percent, and even more preferably atleast about 30 percent as measured for a single property, preferablywith no substantial deleterious effect on the extrudability propertiesof the composition or on the properties of commercial interest of theextrudate produced therefrom. More preferably, as measured relative tothe extrudability of the extrudable mass in the absence of the lubricantcomposition, the lubricant composition is present in an amount effectiveto improve, by at least about 1 percent, more preferable by more thanabout 2 percent, and more preferably by more than about 5 percent, twoor more properties associated with the extrudability of the compositionand/or the commercial value of an extrudate product extruded therefromwith no substantial deleterious effect on any other of those properties.The extrudability of an extrudable mass can be measured by any one ofseveral characteristics of the extrudable mass, as described in detailhereinafter. Also described in detail hereinafter is the measurement ofseveral aspects of commercial value of extrudate product prepared froman extrudable mass.

Another aspect of the present invention provides extruded compositionsformed from the extrudable composition of the present invention and/orin accordance with the process of the present invention.

According to another aspect of the present invention, shaped articlesare provided based upon and/or formed using the extrudable compositionsand/or the extrusion methods of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Although it is contemplated that the present invention will have thegreatest applicability in connection with extrusion of thermoplasticpolymers reinforced with cellulose materials, for example, PVC polymers(also sometimes referred to herein for convenience as PVC resin)reinforced with wood fiber, it is believed that it will also haveapplicability to other extrudable compositions containing a reinforcingmaterial. For example, ram extrusion of reinforced polymer compositionscontaining one or more polymers that are not strictly thermoplastic,such as polytetrafluoroethylene (PTFE), may be beneficially affected bythe present invention. Therefore, the term “extrudable composition” isused herein to refer not only to compositions that contain polymershaving thermoplastic properties reinforced with cellulose reinforcingmaterial, but also those polymers that are readily extrudable and/orbehave similar to thermoplastic polymers with respect to extrusionprocesses and which are combined with a reinforcing material havingproperties similar to those of cellulose reinforcing material.Compositions of such extrudable polymers, whether thermoplastic orotherwise, and such reinforcing materials, whether cellulose orotherwise, are sometimes referred to herein for convenience asreinforced resins.

The Methods

The present invention is directed in one aspect to methods of formingshaped articles from an extrudable composition. Generally, the firststep is to provide an extrudable composition in accordance with thepresent invention. Although it is contemplated that the extrudablecomposition of the present invention may be provided by any means knownin the art, it is generally preferred that the extrudable composition isformed by combining at least a resin, a reinforcing material, and aspecific combination of components which together have a beneficiallubricating effect on the extrudable composition. This combination ofcomponents may also be provided as a separate lubricant compositionaccording to certain aspects of the present invention.

As is known in the art, the requirements of an extrudable compositionvary widely depending on the equipment being used and the desiredproperties of the extrudate, among other factors, and all suchextrudable compositions are within the scope of the present invention.Generally, these conditions include mixing the resin, the combination oflubricant components of the present invention, and one or more othercomponents that may be present. Preferably, the blending step causesshear heating within the composition, and the combination of shear andheat cause the individual particles of the composition to soften andfuse, creating a substantially homogeneous mass. At the point of fusing(fusion point), the identity of individual particulates in thecomposition is preferably substantially lost.

When such heating and blending is performed under known standard testingconditions, the period of blending required to reach the fusion point isreferred to as the “fusion time.” Generally, at the fusion point, theviscosity of the composition is at a maximum, and it is at about thissame point that a maximum will occur in the torque required to blend themass. The torque maximum is related to the fusion viscosity and isreported as fusion torque. With continued blending, it is expected thatthe viscosity of the composition, and the torque required to blend thecomposition, will decrease to a relatively steady state condition. Thesteady state value is referred to as the equilibrium viscosity, thetemperature of the composition at this point is referred to as theequilibrium temperature, and the torque required to blend thecomposition at this point is referred to as equilibrium torque. Withfurther continued blending, it is expected that the composition wouldbegin to cross-link and the viscosity of the composition, and hence theblending torque, would begin to rise. The elapsed time between thefusion point and the beginning of a measurable rise in viscosity due tocross-linking is referred to as the stability time.

The methods of the present invention also include extruding the providedextrudable composition to form a shaped article. Preferably, theextrusion step includes bringing the extrudable composition of thepresent invention to a temperature at which it can undergo plastic flow.In preferred embodiments this comprises heating the extrudablecomposition and forcing the extrudable composition through a diecontaining one or more openings to impart a profile shape to theemerging extrudate.

One characteristic of the preferred methods of the present invention,and a technique which can be used to measure the extrudability, relatesto the amount of force required to force the extrudable composition ofthe present invention through the die. Preferably, the step of forcingthe extrudable composition through a die advantageously requires anamount of force which is lower in comparison to other methods capable ofproducing an extrudate of comparable quality to that which can beproduced in accordance with the present invention. It is preferred touse the combination of lubricant components of the present invention inamounts that together are effective to reduce the force required toforce the extrudable composition through the die by at least about 2percent, more preferably by at least about 5 percent, and even morepreferably at least about 10 percent, relative to the force required toforce the extrudable composition through the die, when compared to anextrudable mass in which the lubricant composition is absent and withall other conditions being substantially the same. In such embodiments,it also generally preferred that the extrudability properties of theextrudable composition are not substantially degraded, and the physicaland mechanical properties of an extrudate product produced from theextrudable mass, as described in detail below, are not substantiallydegraded. More preferably, an amount of the present lubricantcomposition is used which provides a reduction in the force required toforce the extrudable mass through the die by at least about 2 percent,more prefereably by at least about 5 percent, and even more preferablyat least about 10 percent, with a concomitant increase by at least about1 percent, more preferably at least about 2 percent in the tensileand/or flexural strength of an extrudate product prepared from theextrudable mass.

Although applicants to not intend to be bound by or to any particulartheory of operation, in general it is believed that lubricants added toextrudable compositions can have either or both internal and externallubrication properties. In general it is believed that an “internallubricant” properties effect the processability of the composition byreducing the cohesive forces which impart viscosity to the composition.By lowering these forces, it is believed that the polymer moleculeswhich make up most of the mass of the composition are able to moreeasily “slip” past each other with greater ease when pressure isapplied. In this manner, internal lubricants produce a decrease in theapparent viscosity of the extrudable composition, which is anothermeasure of extrudability. This reduction in cohesive ability of theresin in general also leads to a reduction in the tensile strength of anextrudate product produced from the extrudable composition. Thepreferred extrudable compositions of the present invention requirecomparatively lower force to impart plastic flow to the composition, andyet retain or improve the strength of an extrudate product prepared fromthe extrudable composition prepared in accordance with the invention.

Without being bound by or to any particular theory, it is generallybelieved that an external lubricant exudes from the mass of anextrudable composition and acts at the interface of the composition anda surface contacting the composition, for example at the point ofcontact between a die and an extrudable composition. This in turnreduces the force required to overcome flow resistance through a conduitor an orifice (resistance to plastic flow) and also beneficiallyimproves the surface qualities of extrudate, such as an increase in thesmoothness of the surface of an extruded article. However, without beingbound by or to any particular theory, it is generally believed that anexternal lubricant also acts at the interface of the resin whichsubstantially comprises an extrudable mass and a reinforcing body withinthat mass, for example, a wood fiber, lubricating that interface andconcomitantly decreasing the interaction between the resin and thefiber. This reduced interaction permits the reinforcing body to “pullout” of the mass more easily, reducing the strength of an extrudateproduct prepared from such an extrudable mass. Preferably, the lubricantcomposition of the present invention is used in an amount which providesnot only at least about a 2 percent reduction, more preferably at leastabout a 5 perecent reduction, and more preferably at least about a 10percent reduction in the resistance of an extrudable composition toplastic flow, but provides at least about a 1 percent, more preferablyat least about a 2 percent, and more preferably at least about a 5percent increase in the flexural and/or tensile strength of an extrudateproduct prepared from the extrudable composition.

The preferred methods of the present invention are thus capable ofproviding an extrusion step utilizing a relatively low head pressure anda relatively low torque required to drive the extrusion process, each ofwhich is also a characteristic by which the extrudablity of theextrudable composition can be measured. In certain embodiments, thelubricant composition is preferably present in the composition in anamount effective to reduce the head pressure by at least about 5percent, more preferably by at least about 10 percent, relative to thehead pressure required with all other conditions being substantially thesame except for the presence of the lubricant composition, andconcomitantly provide at least about a 1 percent, more preferably atleast about a 2 percent increase in tensile and/or flexural strength ofan extrudate product prepared from the extrudable composition. It isalso preferred in certain embodiments that the lubricant composition ispresent in the extrudable composition in an amount effective to reducethe extrusion torque by at least about 2 percent, more preferably by atleast about 5 percent, and even more preferably at least about 10percent, relative to the extrusion torque required with all otherconditions being substantially the same except for the presence of thelubricant composition and concomitantly provide at least about a 1percent, more preferably at least about a 2 percent increase in tensileand/or flexural strength of an extrudate product prepared from theextrudable composition.

Certain preferred methods of the present invention are thus capable ofproducing extrusion product having greatly improved dimensionalstability. Preferably the lubricant composition is present in theextrudable composition in an amount effective to increase thedimensional stability of the extruded product by at least about 2percent, more preferably by at least about 5 percent, and even morepreferably at least about 10 percent, relative to the dimensionalstability of the extruded product with all other conditions beingsubstantially the same except for the presence of the lubricantcomposition and concomitantly provide at least about a 1 percent, morepreferably at least about a 2 percent increase in tensile and/orflexural strength of an extrudate product prepared from the extrudablecomposition.

Once again, while applicants do not intend to be bound by or to anyparticular theory, it is believed that the compositions and processes ofthe present invention are capable of achieving this desirable resultbecause less energy, whether in the form of heat and/or tourque, isrequired to impart plastic flow to the extrudable composition of thepresent invention. Importantly, the preferred embodiments of the presentinvention achieve this advantageous decrease in extrusion energy, whichis an indication of improved extrudability, without any substantialsacrifice or deterioration in dimensional stability, and with aconcomitant beneficial increase in tensile strength in the extrudedproduct. Dimensional stability is assessed by observing the amount bywhich an extruded shape expands during solidification after it emergesfrom a die. Such expansion is sometimes referred to as die swell.Relatively low extrusion temperatures can be employed in accordance withthe preferred methods of the present invention, and thus the extrudedmaterial solidifies sooner after leaving the die. Furthermore,relatively low extrusion pressures can be developed in accordance withthe preferred methods of the present invention, thereby resulting in alowering of the residual elastic forces within the emerging extrudate.It is believed that the reduction in the amount of energy which must bedissipated by expansion of the material upon emerging from the diemanifests as a desirable reduction in die swell.

As discussed above, and again without wanting to be bound by or to anyparticular theory, an external lubricant reduces the adhesion between anextrudable composition and a surface contacting the composition. Whenthe extrudable composition contains a reinforcing material, the tendencyof the resin, which comprises to a substantial degree the bulk of thecomposition, to adhere to the die during extrusion, can act to pullreinforcing materials from the extrudable composition as it is leavingthe die. This tendency yields a surface on an extrudate product whichhas a grainy or even pitted (“corn cobb”) appearance, lowering thecommercial value of the extrudate. The quality of the extrudate surfaceis typically assessed by measuring its reflectivity (gloss). Themeasurement of gloss is known, for example, ASTM standards D-2523-95 andD2457-97. Preferably the lubricant components of the present inventionare present in the extrudable composition in an amount, when takentogether, is effective to increase the gloss of the extruded product byat least about 2 percent, more preferably by at least about 5 percent,and even more preferably at least about 10 percent, relative to thegloss of the extruded product with all other conditions beingsubstantially the same except for the presence of the lubricantcomposition and concomitantly provide at least about a 1 percent, morepreferably at least about a 2 percent increase in tensile and/orflexural strength of an extrudate product prepared from the extrudablecomposition.

It may be found that certain lubricant compositions of the presentinvention may also act as a surfactant by improving wetting between (andthereby adhesion between) a reinforcing material and the resin componentof the composition.

Applicants have discovered lubricant compositions which, in preferredembodiments, provide one or more improved extrudability properties (forexample, lowered extrusion torque) and/or one or more improvedmechanical and/or physical properties of the extrudate product preparedtherefrom (for example, improvement in dimensional stability, surfacegloss, tensile strength and flexural strength). The measurement of thevarious extrudability properties and of surface gloss was discussedabove. The measurement of tensile and flexural strength of an extrudedarticle is also known (see, for example, ASTM D 638 and D 6109respectively, each of which is incorporated herein by reference).

As it emerges from the orifice opening, the extrudate is preferablycooled to produce a relatively rigid article having the basic shapeimparted by the die. The shaped extrudate can be used either in itsextruded form, for example, as a decorative molding, as fencing members,as siding for buildings, as windows members, as door jambs, as baseboard, as flashing, and like products, and all such products produced bythe present methods or using the present compositions are within thescope of the present invention. The extrudate also may be cut intoconvenient length pieces and packaged for use in follow-on processing,for example, as feedstock for a injection or blow molding processes.

The present methods in preferred embodiments therefore compriseproviding an extrudable composition comprising at least one polyvinylchloride resin, a cellulose reinforcing constituent, and a lubricantcomposition of the invention in an amount effective to improve, relativeto the properties of the same composition but in the absence thelubricant composition, at least one measure of extrudate quality whilepreferably maintaining at least one, and preferably a plurality of,extrudability properties. Preferably, the methods of the presentinvention produce improvement in at least one measure of extrusionperformance and in one measure of extrudate quality. More preferably,the present methods exhibit improved performance in one or more of thefollowing: extrudability criteria (such as extrusion torque, headpressure and processing stability); a physical property of an extrudateproduct prepared from the extrudable composition (such as surface glossand dimensional stability); a mechanical property of the extrudedarticle (such as flexural strength and tensile strength).

The Compositions

The present invention provides extrudable compositions, additivecompositions (including lubricant compositions) useful in theformulation of extrudable compositions, and extruded compositions(including shaped articles) formed from the extrudable compositions ofthe present invention.

The Extrudable Compositions

The extrudable compositions of the present invention include a resin, areinforcing material, and a combination of oxidized polyethylene wax,ester wax, and amide wax. In addition, the present extrudablecompositions may optionally include other additives, including otherlubricant components, impact modifier(s), filler(s), heat stabilizer(s),processing aid(s), binder(s), colorant(s), and other processing aid(s),for example, those described in Handbook of Plastic Materials andTechnology, Ed. I. Rubin, Wiley-Interscience, John Wiley & Sons, Inc.New York, 1990 and those described in Plastics Additives and ModifiersHandbook, Ed. J. Edenbaum, Van Nostrand Reinhold, New York 1992, Chapter3, each of which is incorporated herein by reference.

The preferred extrudable compositions of the present invention exhibitone or more of the following: improved fusion torque, equilibriumtorque, fusion time, equilibrium temperature, and processing stability(dynamic heat stability) and/or improvements in the dimensionalstability and/or the surface gloss of an extruded article (extrudateproduct) prepared by extruding the extrudable composition. As mentionedabove, these characteristics will generally result in improvements inthe characteristics of the extrusion process and or the appearance andutility, thus the commercial value of an extrudate product. Moreover, inaddition to providing an improvement in one or more of theaforementioned properties, the inventors have found that addition to anextrudable composition of the combination of lubricant componentsaccording to the present invention preferably provides also improvedmechanical properties, for example, flexural and tensile strength. Inother words, the inventors have found that inclusion of lubricantcomponents in accordance with the present invention, described in detailbelow, in a reinforced extrudable composition, preferably a compositioncomprising PVC and a cellulose reinforcing material, can providecompositions which display improved extrudability properties, and/orimprovement in the dimensional stability and/or surface gloss of anextrudate product prepared from the extrudable composition in comparisonto compositions that are substantially the same except for the lack ofthe lubricant composition of the invention, and in addition provide foran extrudate product prepared from these compositions which displaysimproved mechanical properties. In general, with respect to theextrudability properties of the extrudable composition, one or more ofthe following properties will be improved by including in thecomposition the lubricant composition of the present invention: (a)greater dynamic heat stability; (b) lower head pressure; (c) lowerfusion torque; and (d) lower apparent viscosity. In general, withrespect to the physical properties of an extrudate product prepared froman extrudable composition of the invention, improvement in dimensionalstability and/or surface gloss of the extrudate may be observed insteadof or in addition to the extrudability properties mentioned above. Inaddition to improvement in any one of or all of the above mentionedextrudability properties of the extrudable composition and thedimensional stability and surface gloss physical properties of anextrudate product, the extrudable compositions of the present inventionmay display also an improvement in the mechanical properties of tensilestrength and/or flexural strength.

The Resin

The extrudable compositions of the present invention may includethermoplastic resin or resins which exhibit thermoplastic properties orwhich are otherwise extrudable. Thus, it is contemplated that resinssuch as polycarbonates, ABS plastics and high engineering plastics maybe used. It is generally preferred however, that the resin of thepresent compositions comprise, and preferably consist essentially of,vinyl based resin, that is, one or more polymers (includinghomopolymers, copolymers, terpolymers, etc.) that share the vinylradical (CH₂═CH) as a starting structural unit. Particularly preferredis polyvinyl chloride (PVC), and in particular suspension, dispersion,emulsion or bulk PVC resins, with suspension and bulk PVC resins beingpreferred. In preferred embodiments, the PVC resin of the presentinvention has a Filentscher K-value of from about 50 to about 70, andeven more preferably from about 55 to about 65.

The Reinforcing Material

The extrudable compositions of the present invention, and extrudateproducts prepared therefrom, comprise predominantly a resin, describedin detail below, and admixed therewith, substantially homogeneouslydispersed therein, a reinforcing material, also sometimes referred toherein for convenience as a “reinforcing agent”. It will be appreciatedalso that the reinforcing material may have a wide variety of shapes,for example, fibers, chips, and particulates. Although a wide variety ofreinforcing materials may be included (for example, fiber glass, talc,aramide fiber, and the like) preferably the reinforcing materialcomprises a cellulose material (also sometimes referred to herein forconvenience as a cellulose reinforcing constituent). Examples ofsuitable cellulose reinforcing constituents include saw dust, woodchips, wood flour, bisal, hemp and flax. A commercially availablecellulosic reinforcing fiber is, for example, 60 mesh southern yellowpine available from American Wood FiberCo.

Next will be described the various components of the preferred lubricantcomposition, preferred methods for the preparation of the presentextrudable compositions and lubricant compositions, and then examples oflubricant compositions and their use will be presented.

Lubricant Compositions

The preferred lubricant compositions for use in extrudable compositionsof the invention and for use in preparing additive compositions of theinvention comprise: i) at least one oxidized polyethylene wax; ii) atleast one ester wax; and iii) at least one amide wax, preferablybisamide wax.

Oxidized Polyethylene Wax Constituent

Oxidized polyethylene polymers (hereafter oxidized polyethylene or OPE)have been known as surface active materials for many years. Thesematerials are typically prepared from an olefinic polymer, for example,polyethylene, or a “polyethylene wax” olefinic-copolymer, for example,polyethylene/polybutadiene and polyethylene/polymethacrylic acid, bysubjecting the polymer or copolymer to oxidation such that oxygenfunctionality, for example, in the form of carbonyl functional groups,is introduced into the polymer, making it less hydrophobic. Numerouspublications describe the preparation and various uses of thesematerials, for example, U.S. Pat. No. 6,060,565 to Deckers et al., U.S.Pat. No. 4,459,388 to Hettche et al., U.S. Pat. No. 3,322,711 to Bush etal., and U.S. Pat. No. 3,234,197 to Bauum, the disclosures andreferences of which are incorporated herein by reference.

Examples of these materials are available commercially, for example, theA-C® Wax series of oxidized polyethylene materials available fromHoneywell International Inc. (“Honeywell”).

For use in the present invention lubricant compositions, the oxidizedpolyethylene materials most useful have the following properties: i)Brookfield viscosities ranging from about 200 (centipoises) cps at 140°C. to about 85,000 cps at 150° C., acid numbers, as determined by eitherASTM D-1386, 305-OR-1, or TMP-QCL-006 ranging from about 5 mg KOH/g ofmaterial to about 19 g KOH/g of material. It is more preferable for theoxidized polyethylene wax constituent to have a Brookfield viscosity ofat least 6000 cps at 150° C., and an acid number of no greater than 20mg. KOH/g of wax. It is preferred if the OPE component has a Brookfieldviscosity at 150° C. of between about 8,500 cps to about 85,000 cps andan acid number, as determined by ASTM D 638 and D 6109 of from about 7mg KOH/g of material to about 20 mg KOH/g of material. A commerciallyavailable material which is within this range is AC 316 oxidizedpolyethylene, and another is AC 307 oxidized polyethylene, bothavailable from Honeywell.

Ester Wax Constituent

Examples of ester waxes suitable for use in the lubricant and extrudablecompositions of the present invention include polymeric compounds whichcan be prepared by the condensation of a di- or polyfunctionalcarboxylic acid, for example, adipic acid, with a di- or polyfunctionalalcohol, for example, pentaerytritol, in the presence of amonofunctional fatty acid, for example, stearic acid, or othermonofunctional lipophilic organic acid. All of these reactants arearticles of commerce.

Preparation and various uses of various ester waxes have been described,for example, in U.S. Pat. No. 6,485,804 to Nakamachi, et al., U.S. Pat.No. 5,621,033 to Lindner, U.S. Pat. No. 5,039,740 to Anderson et al.,U.S. Pat. No. 4,681,975 to Hasegawa et al., U.S. Pat. No. 4,454,313 toOkitsu et al., and U.S. Pat. No. 3,972,962 to Williams et al., each ofwhich is incorporated herein by reference. In certain preferredembodiments, ester wax suitable for use in the lubricant composition ofthe present invention has the following properties: acid numbers ofbetween about 1 to about 25 mg KOH/g of ester wax; and viscosity of fromabout 30 centipoise at 100° C. to about 160 centipoise at 176° C.

For use in the lubricant compositions of the present invention it ispreferred if the ester wax has an acid number of from about 10 mg KOH/gof wax to about 18 mg KOH/g of wax and has a viscosity of about 50centistokes at 115° C. More preferred are ester waxes comprising thecondensation product of a reaction containing pentaerythritol: adipicacid: stearic acid in the wt. ratio of about 16:14:70 with a residualacid number, as measured by ASTM D-1316 of about 12 mg KOH/g of esterwax, and has a viscosity of about 50 centistokes at about 116° C.

Ester waxes suitable for use in the lubricant composition of the presentinvention are available commercially from Honeywell under the tradedesignation Rheolub™ Specialty esters, including for example, Rheolub™710, Rheolub™ 830, and Rheolub™ 1800.

Other compounds which can be substituted in the present inventionlubricant composition for the ester waxes described above includepentaerythritol-adipate-aleate, pentaerythritol-tetrastearate,pentaerythritol-monostreate, pentaerythritol-distearate, and mixtures oftwo or more thereof. Many of these are available as articles orcommerce, for example, the Pentesters from Cognis.

Amide Wax Constituent

It is contemplated that amide waxes generally are available for use inaccordance with the present invention. It is generally preferred,however, that the amide wax component comprises, and preferably consistessentially of, and even more preferably consist of, bisamide wax.Examples of suitable bisamide wax for use in the lubricant compositionof the present invention are those which can be prepared by thecondensation of a diamine, for example, ethylenediamine, with one ormore species of fatty acid, for example, stearic acid. This results in acompound having di-terminal fatty acid residues bonded terminally to acentral alkyl moiety via amide groups. It will be appreciated that anycarboxylic acid could be used in this condensation as well as mixturesof various carboxylic acids. Additionally, any di- or polyfunctionalamine could be used. All of these reactants are articles of commerce.

Preparation and various uses of various bisamide waxes have beendescribed, for example, in U.S. Pat. Nos. 4,812,504 and 4,607,072 to Su,and U.S. Pat. No. 4,032,473 to Berg et al., the disclosures andreferences of which are incorporated herein by reference.

For use in the lubricant compositions of the present invention it ispreferred if the bisamide wax comprises a copolymer of stearic acid andethylenediamine with a base value of about 1 mg of KOH/g of bisamidewax, a residual acid number of from about 5 mg KOH/g of wax to about 9mg KOH/g of bisamide wax, and has a melting point of about 138° C.

Bisamide waxes suitable for use in the lubricant composition of thepresent invention are available commercially as the Advawax series ofwaxes from Rohm & Haas Corporation. Particularly useful is Advawax™ 280.

Other known amide waxes useful in the present invention lubricantcomposition include eurucamide, oleocamide, and stearamide.

The lubricant compositions of the present invention preferably compriseoxidized polyethylene in an amount up to about 22 wt %, ester wax in anamount up to about 39 wt %, and amide wax in an amount up to about 39 wt%, based on the weight of the lubricant composition. For use in mostextrudable compositions, lubricant compositions of the present inventionwill comprise: (a) from about 5.0 wt % to about 50 wt. %, preferablyfrom about 10 wt. % to about 40 wt. %, more preferably from about 15 wt.% to about 25 wt. % of one or more oxidized polyethylene waxconstituents; (b) from about 6.5 wt % to about 60 wt. %, preferably fromabout 20 wt. % to about 60 wt. %, more preferably from about 30 wt. % toabout 50 wt. %, and even more preferably from about 35 wt. % to about 50wt. % of one or more ester wax constituents; and (c) from about 6.5 wt.% to about 60 wt %, preferably from about 20 wt. % to about 60 wt. %,more preferably from about 30 wt. % to about 50 wt. %, and even morepreferably from about 35 wt. % to about 50 wt. % of one or more amidewax (preferably bisamide wax) constituents. Compositions having amountslying outside these ranges may also be used as required by theextrudable composition into which the lubricant composition of thepresent invention is to be incorporated.

In certain embodiments the lubricant compositions of the presentinvention comprise from about 6.5 wt % to about 22 wt. % of oxidizedpolyethylene constituents, from about 6.5 wt % to about 39 wt. % of oneor more ester wax constituents and from about 6.5 wt. % up to about 39wt % of one or more amide wax (preferably bisamide wax) constituents.Another preferred lubricant composition comprises from about 18 andabout 19 wt % of one or more oxidized polyethylene constituents, fromabout 38 and about 39 wt. % of one or more ester wax constituents andfrom about 42 and about 43 wt. % of one or more amide (preferablybisamide) wax constituents.

It will be appreciated that, guided by known principles, values of theseconstituents lying outside of these preferred ranges can be employed andremain within the scope of the invention.

Additives

As mentioned above, extrudable compositions of the present invention mayinclude also other additives typically included in extrudablecompositions, preferably PVC resin, as described above, including thoseadditives which have heat-stabilizing properties and including alsothose which have internal and external lubricant properties. Herein,these are termed “supplemental” to distinguishing them from thelubricant compositions of the invention which also have lubricating andheat stabilizing properties. Accordingly, the amount of lubricantcomposition employed and the amounts of constituents comprising thelubricant composition can be adjusted according to amount ofsupplemental lubricants, stabilizers, etc. in the composition inaccordance with known principles.

Examples of supplemental heat stabilizers include any of thesupplemental additives known to exert a dynamic heat-stabilizing effectwhen added to an extrudable PVC composition. Examples of supplementalheat stabilizers suitable for use in the present compositions includethose generally used as heat stabilizing additives in extrudable PVCcompositions, for example, compounds containing tin, for example, tinmercaptides. Other art-recognized heat stabilizers, for example, thosedescribed generally in the Plastics Additives and Modifiers Handbook,Ed. J. Edenbaum, Van Nostrand Reinhold, New York 1992 (which areincorporated herein by reference), for example, those based onlead-based compounds, for example, neutral lead stearate and dibasiclead phosphate. Further examples include “mixed-metal” soaps, forexample calcium/zinc stearates. Additionally, heat stabilizers which arenot based on heavy metal salts may be used, for example, organic-basedstabilizers (OBS) from Crompton Corporation.

A further example of a supplemental additive includes a metallic soapprepared “in situ” by addition of calcium hydroxide and a fatty acid tothe composition. In general, when the composition contains fatty acidand calcium hydroxide constituents, the composition is preferablyprepared by blending together a wax in liquid form and a fatty acid,followed by a reaction step carried out under conditions in which atleast a portion of the fatty acid is neutralized, as dictated byart-recognized variables with regard to the properties desired in theextrudable PVC composition into which the finished additive compositionis to be blended. Preferably, the mixing and temperature conditionsattained during the blending of the constituents of additivecompositions which include a fatty acid and calcium hydroxide areadjusted to insure that the neutralization reaction between thehydroxide and the acid proceeds substantially to completion.

An example of a supplemental lubricant is polyethylene wax homopolymer.Such materials are known and are available under from Honeywell underthe trade designation AC® series of wax homopolymers.

Preparation of Extrudable Compositions

The lubricant compositions of the present invention may be prepared byany known means of blending solid, semi-solid, or liquid materials withother solid, semi-solid, or liquid materials.

Conveniently, an extrudable composition can be prepared by placing anamount of resin, preferably a polyvinyl chloride resin (PVC resin) intoa blending apparatus, adding in turn the reinforcing constituent(s), thedesired supplemental additive constituents, for example, stabilizers,fillers, processing aids, colorants, and pigments, and other ingredientsdesired in the composition, and adding to the mass the presentcombination of lubricant constituents. As indicated above, the lubricantcomponents which comprise the present combination can be blendedseparately, preferably in accordance with the proportions describedabove and added, in the amounts specified herein, in a single additionas a blend of the lubricant constituents to the above-mentionedresin-containing mixture. Alternatively, the individual components whichcomprise the present combination may be added separately, at the sametime or at different times, to one or more of the other components ofthe extrudable composition. Any type of mixing or blending equipment ona scale from manual laboratory bench top scale, for example a hand-heldmotorized mixer and vessel, to motorized industrial scale processingequipment can be used. Examples of the latter type of equipment includea Henschel mixer, a ribbon blender, and a temperature controlledagitated blend tank.

It will thus be appreciated that the order of mixing the components isnot critical. For example, any two or more lubricant components(including all of the lubricant components) which comprise the presentlubricant combination may be prepared as an admixture which is addedinto an extrudable composition of the type described above, or eachcomponent may be added, either simultaneously or sequentially, to one ormore of the other components of the extrudable composition of the typedescribed above. Alternatively, the resin and various constituents ofthe extrudable composition could be added to one or more (including all)of the lubricant components of the present lubricant combination. Thus,all such means of bringing the components of the present extrudablecomposition together are contemplated by the term “adding to” usedherein.

In general, the lubricant components of the present combination arepresent in the extrudable composition such that, in the aggregate, theamount of lubricating components is sufficient to provide an extrudablecomposition requiring less equilibrium torque and/or having a lowerequilibrium temperature and/or increase the smoothness of the surface(gloss) of an extrudate product produced from the composition and/orprovide for increased dimensional stability of an extrudate productproduced from the composition, as determined by comparison with acomposition which is similar except for the addition of the lubricantcombination of the present invention, and at the same time preferablyprovides for an increase in the tensile and/or flexural strength of anextrudate product prepared from the improved extrudable compositionrelative to the extrudable composition which is the same except for theinclusion of a lubricant combination of the present invention. It ispreferred that the lubricant combination is used in an amount thatreduces equilibrium torque and/or equilibrium temperature by at leastabout 3% as measured in a torque rheometer. It is also preferred to addan amount of the lubricant composition providing at least about a 10%increase in tensile and/or flexural strength as measured in accordancewith ASTM D 638 and D6109 respectively. Although this amount will vary,in general it is preferred if the improved composition contains,relative to 100 weight part of extrudable resin (preferably PVC resin)in the extrudable composition, up to about 0.75 weight parts (PHR) ofoxidized polyethylene, up to about 1.5 PHR of ester wax, and up to about1.5 PHR amide wax, preferably bisamide wax.

In general, the desired amounts of the various constituents of alubricant composition will be provided to an extrudable composition bythe addition of from about 0.5 to about 6 wt. parts of a lubricantcomposition described above per hundred weight parts of resin (PHR) inthe extrudable composition, preferably from about 1 PHR to about 5.5 PHRof lubricant composition will be added to an extrudable composition andmost preferably from about 2.0 PHR to about 5.0 PHR of lubricantcomposition will be added to the extrudable composition. Greater orlesser amounts may be used, guided by known principles and inconsideration of the properties desired of the extrudable compositionand the supplemental additives which may be present in an extrudablecomposition. For example, extrudable compositions into which thelubricant compositions of the present invention are added may alsoinclude other internal and external lubricants. Accordingly, the amountof lubricant composition employed will be adjusted to a greater orlesser amount as is warranted by the inclusion or exclusion of otherlubricating components.

In one embodiment, the extrudable compositions of the present inventionpreferably comprise:

-   -   (a) 100 wt. parts of one or more extrudable resins (preferably        comprising and even more preferably consisting essentially of        PVC resin);    -   (b) from about 10 PHR to about 250 PHR, preferably from about 30        PHR to about 200 PHR, and more preferably from about 30 PHR to        about 160 PHR of reinforcing agent, preferably comprising and        even more preferably consisting essentially of cellulose        reinforcing agent;    -   (c) from about 0.1 PHR to about 3.6 PHR of amide wax (more        preferably from about 0.1 PHR to about 2.1 PHR amide wax, and        even more preferably from about 0.7 PHR to about 2.0 PHR amide        wax), with bisamide wax being preferred;    -   (d) from about 0.025 PHR to about 3 PHR of oxidized polyethylene        wax (more preferably from about 0.1 PHR to about 3 PHR oxidized        polyethylene wax, and even more preferably from about 0.3 PHR to        about 1.3 PHR oxidized polyethylene wax);    -   (e) from about 0.1 PHR to about 3.6 PHR of ester wax (more        preferably from about 0.2 PHR to about 2 PHR ester wax, and even        more preferably from about 0.3 PHR to about 1.3 PHR ester wax);    -   (f) from about 0.4 PHR to about 2 PHR, preferably from about 0.5        to about 1.5, more preferably from about 0.6 PHR to about 1.0        PHR of one or more paraffin wax constituents;    -   (g) up to about 15 PHR, preferably from about 1 PHR to about 10        PHR, more preferably from about 2 PHR to about 7 PHR of calcium        carbonate;    -   (h) from about 0.5 PHR to about 2.0 PHR, preferably from about        0.8 PHR to about 1.8 PHR, more preferably from about 0.8 to        about 1.7 PHR of one or more tin stabilizers; and optionally one        or more of the following    -   (i) up to about 10 PHR, preferably from about 0.5 PHR to about        7.0 PHR, more preferably from about 0.5 to about 5.0 PHR of one        or more processing aids;    -   (j) up to about 15 PHR, preferably up to about 10 PHR, more        preferably up to about 7 PHR of one or more modifiers;    -   (k) from about 0.3 PHR to about 2.0 PHR, preferably from about        0.4 PHR to about 1.5 PHR, more preferably from about 0.5 to        about 1.0 PHR of calcium stearate;    -   (l) up to about 1 PHR, preferably up to about 0.5 PHR, more        preferably up to about 0.1 PHR of one or more polyethylene wax        homopolymer constituents.

In certain preferred embodiments the extrudable compositions of thepresent invention preferably comprise:

-   -   (a) 100 wt. parts of one or more PVC resin constituents;    -   (b) from about 10 wt. parts to about 250 wt. parts, preferably        from about 30 wt. parts to about 200 wt. parts, and more        preferably from about 30 to about 160 weight parts of one or        more cellulose reinforcing constituents;    -   (c) from about 0.5 PHR to about 6.0 PHR of a lubricant        composition comprising:        -   (i) from about 20 wt. % to about 60 wt. % of amide wax            (preferably bisamide wax);        -   (ii) from about 5 wt. % to about 50 wt. % of polyethylene            wax constituents; and        -   (iii) from about 20 wt. % to about 60 wt. % of ester wax,        -   preferably from about 1.0 PHR to about 5.5 PHR of a            lubricant composition comprising:        -   (i) from about 30 wt. % to about 50 wt. % of one or more            bis-amide wax constituents;        -   (ii) from about 10 wt. % to about 40 wt. % of one or more            oxidized polyethylene wax constituents; and        -   (iii) from about 30 wt. % to about 50 wt. % of one or more            ester wax constituents,    -    more preferably from about 2.0 PHR to about 5.0 PHR of a        lubricant composition comprising:        -   (i) from about 35 wt. % to about 50 wt. % of one or more            bis-amide wax constituents;        -   (ii) from about 15 wt. % to about 25 wt. % of one or more            oxidized polyethylene wax constituents; and        -   (iii) from about 35 wt. % to about 50 wt. % of one or more            ester wax constituents,    -   (d) from about 0.4 PHR to about 2 PHR, preferably from about 0.5        to about 1.5, more preferably from about 0.6 PHR to about 1.0        PHR of one or more paraffin wax constituents; and optionally    -   (e) up to about 15 PHR, preferably from about 1 PHR to about 10        PHR, more preferably from about 2 PHR to about 7 PHR of calcium        carbonate;    -   (f) from about 0.5 PHR to about 2.0 PHR, preferably from about        0.8 PHR to about 1.8 PHR, more preferably from about 0.8 to        about 1.7 PHR of one or more tin stabilizers;    -   (g) up to about 10 PHR, preferably from about 0.5 PHR to about        7.0 PHR, more preferably from about 0.5 to about 5.0 PHR of one        or more processing aids;    -   (h) up to about 15 PHR, preferably up to about 10 PHR, more        preferably up to about 7 PHR of one or more modifiers;    -   (i) from about 0.3 PHR to about 2.0 PHR, preferably from about        0.4 PHR to about 1.5 PHR, more preferably from about 0.5 to        about 1.0 PHR of calcium stearate;    -   (j) up to about 1 PHR, preferably up to about 0.5 PHR, more        preferably up to about 0.1 PHR of one or more polyethylene wax        homopolymer constituents.

Additive Compositons

The lubricant compositions of the present invention can be added tovarious supplemental, reinforcing, and resin constituents to provide foran extrudable resin composition. These lubricant compositions can beused in conjunction with existing extrudable resin compositions, forexample PVC compositions, as lubricant additives which can provide alsoimproved extrudablity properties and improved physical and mechanicalproperties in an extrudate product prepared therefrom. Examples ofcellulose-reinforced PVC-containing extrudable compositions to which thelubricant composition of the present invention may be added to providean extrudable composition of the present invention are described in U.S.Pat. No. 6,248,813 and U.S. Pat. No. 6,103,791 to Zehner and U.S. Pat.No. 6,210,792 to Seethamraju et al., the disclosures and references ofwhich are incorporated herein by reference.

The above-described lubricant compositions can form the basis of anadditive composition which contains in addition to the lubricantconstituents, one or more supplemental additives, such as supplementalinternal and external lubricants, heat stabilizers, and otherconstituents of extrudable PVC compositions and the variables governingthe selection and amounts of these supplemental additives used inextrudable PVC compositions are described generally in the PlasticsAdditives and Modifiers Handbook, Ed. J. Edenbaum, Van NostrandReinhold, New York 1992, which is incorporated herein by reference.Preferred additive compositions comprise the above-described lubricantcomposition of the invention and at least one member of the groupconsisting of compatible supplemental lubricants and compatiblesupplemental heat stabilizers.

For example, in one embodiment, an additive composition of the presentinvention may be formulated to comprise substantially all of theconstituents, except for the extrudable resin, of an extrudablecomposition. An additive composition of this type is preferablyformulated to be mixed with only an extrudable resin, such as extrudablePVC resin, and thereby provide an extrudable PVC composition. In analternative embodiment, an additive composition may be formulated to beadded to an extrudable PVC composition as one of many additiveconstituents used to prepare the extrudable composition. In such anembodiment, it is preferred for the present additive composition tofurther comprise at least some of the most common constituents ofextrudable PVC compositions, thereby providing a single additivecomposition which can be used in a number of different extrudable PVCcompositions while reducing the number of addition processes required toprepare an extrudable PVC composition.

It is contemplated that a wide variety of components over a wide rangeof relative ratios will be adaptable for use in the present invention inview of the teachings contained herein.

As described above for extrudable compositions, additive compositions ofthe present invention may be prepared by any known means for admixingsolid, semi-solid, or liquid materials with other solid, semi-solid, orliquid materials, including techniques used for the admixture ofmiscible materials, for example a mixture of two or more componentsforming a single phase, and techniques used for blending phase separatedmaterials to form an intimate interpenetrating structure ofdomain-separated regions of two or more immiscible or partiallyimmiscible materials. As will be appreciated also, except forembodiments in which a reaction between two constituents is carried outto generate a constituent of the composition in situ, for example, theprovision of a metallic soap lubricant, the various constituents ofadditive compositions may be blended together in any order and remainwithin the scope of the invention.

It will be appreciated that extrudable cellulose-reinforced PVCcompositions which may be improved by the addition of a lubricantcomposition of the present development may comprise a wide range ofcomponents present in various amounts in accordance with knownprinciples. The processing properties of these compositions will beimproved to a varying degree with the addition of an aliquot of thelubricant composition of the present invention. Additionally, thephysical properties of articles formed from these compositions will beimproved with the addition of a lubricant composition of the presentinvention to the extrudable composition prior to forming it into anarticle.

The following examples are presented for the purpose of illustrating theforgoing description and are not meant to limit the scope of the claimedinvention.

EXAMPLES

Compositions corresponding to a reinforced PVC resin-containingextrudable composition which does not contain a lubricant composition ofthe present invention (Comparative Examples A (Table I) and B (TableIII)) and one which corresponds to a cellulose reinforced PVCresin-containing extrudable composition containing a lubricantcomposition of the present invention (Example 1, Table 1, and Example 2,Table III) were prepared with the components in the weight parts shownin Tables I and II below. The materials used to prepare the example andcomparative example compositions were as follows: 1091® polyvinylchloride resin (resin) from Georgia Gulf; TM281® tin based heatstabilizer (stabilizer) from Rohm & Haas; Rheolub® 165 paraffin wax(paraffin wax) from Honeywell, COAD 10® calcium stearate (calciumlubricant) from Norac; K120N acrylic processing aid (processing aid)from Rohm & Haas; KM334® acrylic impact modifier (impact modifier) fromRohm & Haas; UFT® calcium carbonate from OMYA (calcium carbonate); woodflour as a cellulose reinforcing component from American Wood Fiber;polyethylene wax (CS 600 from Honeywell); oxidized polyethylene wax(OPE) AC 316 A (Honeywell); Ethylene bis-stearamide (bisamide wax)Adavawax 280 (Rohm & Haas); and Rheolub 710 (ester wax) (Honeywell). Allmaterials were used as received.

TABLE I Wt. Parts relative to 100 weight parts resin ConstituentComparative Example A Example 1 Cellulose reinforcing 50 50 (vol. % ofbulk) (vol. % of bulk) Resin 100 100 Stabilizer 1.6 1.6 Paraffin wax 1.00.7 Polyethylene wax — 0.04 Calcium lubricant 1.2 0.7 Processing aid 1.20.5 Lubricating process aid 1.0 — Impact modifier 5.0 5.0 Calciumcarbonate 5.0 OPE* — 0.5 Ester wax* — 1.02 Bisamide wax* — 1.14*component of the lubricant composition of the present invention

The compositions were prepared by charging the constituent componentsinto a Waring Blender (high intensity mixer) and heating to atemperature in excess of 105° C. while operating the mixing blades. Whenthe components were homogeneously blended, the composition wasdischarged, cooled to ambient temperature and left to stand for 24 hours(aging period).

At the end of the aging period a 68 g sample of the composition wasplaced into a Brabender torque rheometer and subjected to rheometricanalysis. As described above, each composition was subjected torheometric analysis of the fusion and stability time, equilibrium andfusion torque and equilibrium temperature according to ASTM standardtesting procedure D2538. Using this procedure, comparison of the statedrheometric properties was made between Example 1 and Comparative ExampleA. This comparison showed that on average the fusion temperature was 2%lower, the fusion torque was 10% less, for the extrudable compositioncontaining a portion of a lubricating composition of the presentinvention than for Comparative Example A, which contained onlyart-recognized lubricants in typical proportions. These data show thatthe lubricant composition of the present invention improves theprocessability of an extrudable cellulose-reinforced PVCresin-containing composition.

Aliquots of each extrudable composition were used to prepare shapedarticles by placing them into a twin screw extruder and forming solidrectangular profile shapes. These shapes were compression molded, cut,and milled to prepare specimens according to the ASTM standards. Thespecimens were then subjected to testing of the tensile and flexuralstrength according to ASTM D 638 and D 6109 and were visually evaluatedfor surface appearance. These results of this testing are present inTable 2, below.

TABLE II Comparative Property Example A Example 1 Tensile Strength (psi)5460 5643 Elongation (%) 5.65 8.82 Energy (in/lb) 423 514 FlexuralStrength (psi) 9584 9634 Flexural Strain (%) 110.5 102.6 FlexuralModulus (million psi) 1.08 1.15

These data show that the article formed from the extrudable compositionof Example 1 possessed increased tensile and flexural strength, thusdemonstrating that the lubricant composition of the present inventionprovides both improved lubricating properties for processing thecomposition and improves interaction between the reinforcing materialand the PVC resin in the composition.

Visual inspection of the extruded shapes showed that the comparativeexample extrudate was possessed of an extremely rough surface which hada “corn cob” appearance while the extrudate made from the extrudablecomposition of Example 1 was smooth enough to receive a surface finishas extruded.

Example 2 Improved Stability

An extrudable composition showing improved stability will be prepared byadding to an art recognized extrudable composition an aliquot of thelubricant composition of the present invention.

Thus, a lubricant composition used in Example 2 will be prepared bycombining the components in the amounts shown below in Table 3 accordingto the above-described process. It will be found by rheologic comparisonaccording to ASTM 2538 that the thermal stability Comparative Example Bis less than that of Example 2, and the equilibrium torque ofComparative Example B is higher than that of Example 2, notwithstandingthat both of the compositions have equal amounts of lubricant.

It will be found that the composition of Comparative Example B hasinsufficient stability to provide an extruded article. It will also befound that the extrudable composition of Example 2, which is essentiallythe same as Comparative Example B but with the addition the lubricantcomposition of the present invention, has sufficient stability toprovide an extruded article therefrom. This demonstrates that thelubricant composition of the present invention can provide extrudablecompositions of improved stability.

TABLE III Comparative Example B Example 2 Material PHR PHR PVC Resin 100100 Sn Stabilizer 1.6 1.6 CaCO3 5 5 Impact Modifier 5 5 Process Aid 0.50.5 Paraffin Wax 2.0 0.7 Ca Stearate 2.0 0.7 Low Density OxidizedPolyethylene 0.2 — High Density Oxidized Polyethylene * — 0.5Pentarythritol Adipate * — 1.1 Ethylene bis stearamide * — 1.1 PercentWood Flour 50 50 (percentage of total mixture) * components of thelubricant composition of the present invention

1. An extrudable composition comprising: (a) thermoplastic resin; (b)reinforcing agent comprising cellulose; (c) oxidized polyethylene; (d)ester wax; and (e) amide wax.
 2. The extrudable composition of claim 1wherein said thermoplastic resin comprises polyvinyl chloride (PVC)resin.
 3. The extrudable composition of claim 1 wherein said amide waxcomprises bisamide wax.
 4. The extrudable composition of claim 1 whereinthe combination of (c), (d) and (e) components is present in an amounteffective to reduce the apparent viscosity of said extrudablecomposition relative to the same composition in the substantial absenceof said combination of (c), (d), and (e) components.
 5. An extrudateproduct prepared from the composition of claim 4 having a tensilestrength that is not substantially less than the tensile strength of anextrudate product prepared from substantially the same composition butlacking a combination of (c), (d) and (e) components in a substantialamount.
 6. An extrudate product prepared from the composition of claim 4having a flexural strength that is not substantially less than theflexural strength of an extrudate product prepared from substantiallythe same composition but lacking a combination of (c), (d) and (e)components in a substantial amount.
 7. The extrudable composition ofclaim 1 comprising from about 0.1. PHR to about 3.6 PHR amide wax, fromabout 0.025 PHR to about 3 PHR oxidized. polyethylene wax, and fromabout 0.1. PHR to about 3.6 PHR ester wax.
 8. The extrudable compositionof claim 1 comprising from about 0.1 PHR to about 2.1 PHR amide wax,from about 0.1 PHR to about 3 PHR oxidized polyethylene wax, and fromabout 0.2 PHR to about 2.0 PHR ester wax.
 9. The extrudable compositionof any one of claims 1 to 4 wherein said oxidized polyethylene comprisesa major proportion of oxidized polyethylene having an acid number offrom about 7 to about 20 mg KOH/g and a viscosity of from about 8,500 toabout 85,000 cP at 150° C.
 10. The extrudable composition of any one ofclaims 1 to 4 wherein the oxidized polyethylene component has an acidnumber of from about 10 to about 20 mg KOH/g and a viscosity of fromabout 200 cps to about 1,000 cps at 150° C.
 11. The composition of anyone of claims 1 to 4 wherein the ester wax has an acid number of fromabout 10 to about 14 mg KOH/g and a viscosity of 50 cSt at 240° F. 12.The extrudable composition of any one of claims 1 to 4 wherein the amidewax has an acid number of from about 5 to about 9 mg KOH/g and a meltingpoint of about 280° F.
 13. The extrudable composition of any of claims 1to 4 wherein said combination of components (c), (d) and (e) togethercomprise from about 0.5 PHR to about6PHR.
 14. The composition of any ofclaims 1 to 4 wherein said combination of components (c), (d) and (e)together comprise from about 1.0 PHR to about 5.5 PHR.
 15. Theextrudable composition of claim 4 wherein said components (c), (d) and(e) together are present in an amount effective to improve one or moreextrudability characteristics relative to the same composition butlacking said combination of components (c), (d) and (e), said one ormore improved extrudability characteristics being selected from thegroup consisting of: a) decreased extrusion pressure for a given die andextrusion rate; b) reduced amount of stabilizer needed to achieve thesame degree of stability; c) reduced extruder head pressure for a givendie and extrusion rate; d) reduced extrusion torque for a given die andextrusion rate; e) reduced equilibrium temperature; f) reduced fusiontorque; g) increased surface gloss of an extrudate product prepared fromsaid extrudable composition; and h) increased dimensional stability ofan extrudate product prepared from said extrudable composition.
 16. Theextrudable composition of claim 4 wherein said combination of components(c), (d) and (e) together are present in an amount effective to improveone or more characteristics of an extrudate product prepared from saidextrudable composition relative to the same composition but lacking saidcombination of components (c), (d) and (e), said one or more improvedcharacteristics being selected from the group consisting of: a)increased surface gloss; b) increased flexural strength; and c)increased tensile strength.
 17. An extruded product made from anextrudable composition in accordance with claim 16 wherein the extrudedproduct has an increased tensile strength relative to an extrudedproduct prepared from the same extrudable composition but lacking anysubstantial amount of said combination of components (c), (d) and (e).18. The extruded product of claim 17 wherein said increase in tensilestrength is an increase of at least about 2 percent.
 19. An extrudedproduct made from an extrudable composition in accordance with claim 16wherein the extruded product exhibits an increase in flexural strengthrelative to an extruded product prepared from the same extrudablecomposition but lacking any substantial amount of said combination ofcomponents (c), (d) and (e).
 20. The extruded product of claim 19wherein said increase in flexural strength is an increase of at leastabout 2 percent.
 21. The extrudable composition of claim 16 wherein atleast one of said effected extrudability characteristic is improved byat least about 5 percent.
 22. The extrudable composition of any one ofclaims 1 to 4 wherein the oxidized polyethylene component has aviscosity of from about 200 cps to about 85,000 cps at 150° C.
 23. Theextrudable composition of any one of claims 1 to 4 wherein the oxidizedpolyethylene component has a viscosity of at least about 6000 cps at150° C.
 24. The extrudable composition of any one of claims 1 to 4wherein the oxidized polyethylene component has a viscosity of fromabout 8,500 cps to about 85,000 cps at 150° C.